Lamp receptacle



Feb. 23, 1965 A. 1. APPLETON' LAMP RECEPTACLE I I I It I! I Filed June 21, 1962 Inventor firdzur I. Appleton.

tut/Dow H-Hwrneg-S II I I I 3,170,750 H LAMP RECEPIACLE Arthur I. Appleton, 1 Bridlewood noes, Northbrook, n1.

'Fiiedtlune 21,1962, Ser. No. 204,208 1 Claim. (Cl. 339-180) This invention relates to a lampreceptacle, and in particular to one 'soconstructed as to resist the tendency for a lamp therein to be loosened asa result of vibration.

There are many instances where wall and ceiling vibrations are severe enough to cause loosening of electric lamps in their sockets or receptacles. V Thisfrequenfly occurs, in connection with overhead lights in steelmills, foundries, fabricating plants Where heavy duty stamping or forging equipment is used, and in numerous other kinds of industrial sites. It will be realized that lamps of the screw-in type may be loosened in a back-off direction to such an extent as to separate the electrical contacts, extinguishing the light. Eventually the lamp may be turned by. vibration completely out of its receptacle,

which is adangerous situation. This condition may be ap- ,proached gradually over a period of several days, and it is common practice to have maintenance crews assigned to the task ofchecking.extingui'shedlamps and retightening those which have merely loosened. u

It has; heretofore been proposed to include in the lamp .1 receptacle means for resisting the tendency for the lamp to be loosened by vibrations. Specifically, such means has been in-the form ofprongs-struckinward from the thin-walled side wall of the receptacle shell or socket.

' Such prongs are therefore inherently resilient, and ,prescnt sharp edges so oriented as to resist escape of the lamp in 1a back-ofi direction duelto vibrating ofthe.

receptacle. p

, Escape of the lamp is not completely avoided by such an arrangement, andthe primary object of the present invention is to approach thiside al condition more nearly and todo this other than by merely rnultiplying theprongs aforesaid. Specifically, thisobject-isachieved by forming the center contact of the receptacle with a plurality of spaced, upwardly struck extensions presenting sharp edges 7 which will bite into the. contact :at the base of the'lamp, and yet more specifically, the soft conductor metal at Patented Feb. 23,1 965 of the invention embodying the same or equivalent principles may be used and structural changes may be 1 made as desired by those skilled in the art without departthebase of the lamp, thereby afiordingunusually strong resistance to turning of'the lamp in-a back-olffdir ection.

; There -is another distinct advantage to having extensionsformedon-thecontaet of the receptacle asa-foresaid.

Thus; it was mentioned-above :that maintenance crews are responsible for tightening 'theloos'ened lamps. This condition is observable because, :as noted, a loose lamp is extinguished. Aconsiderable maintenance':iproblem is sometimes entailed depending upon the extent of the lighted area.. It is human nature to procrastinate a precaution, or, as hereto overlook an extinguished lamp for a more pressing problem on the expectation that the actually drop from the socket.

' lampstill has considerable travel left before it will However, under the present invention, the extensions on the center contact, being struck upward there-from, will maintain electrical contact with the base of the lamp 7 throughout a considerable extent of the back-off movement of the lamp, and the lamp will eventually break contact with the aforesaid center contact extensions someing from the present invention appended claim.

. In the drawings: 7

FIG. 1 is a fragmentary plan'view of a lamp receptacle constructed under and in accordance with the present invention;

and the purview "of the FIG."2 is a sectional 'viewoi -the. structure. shown in I FIG. 1 but also showing the base ofsthelamp in association therewith; r

HG 3 is a detail sectional view substantially on the line 3--3 of FIG. 1; and i FIG. 4 is a view partly in elevation and partly in section showing a-di-fferent side of the structure of FIG. 2.

The receptacle of the present invention in its entirety is identified by reference character in the drawing and includes the usual porcelain cup 11 provided with a relatively deep circular cavity 12. .A thin-walled metallic shell 14, formedwith a thread 15,.is secured in the usual fashion in the receptacle recess The receptacle iii as thus far described is of conventional'gor' known construction.

The base of the lamp, 16, includes the usual thread 151 complemental to the thread 15 of the receptacle shell 14. Thelamp is provided with a center contact in the form of a' copper disc and the usuallead bead ZtiB, which is ordinarily of indeterminate extent, in the center area of the copper disc portion of the lamp contact.

The thin-walled metallic :shell is formed with a pair of inwardly struck out iprongs 21 and 22 which as best shown in FIG. 4, are manifest'in L-shaped slits 25 in the wallof the receptacle'shell. .Tllheresultant sharp corners 2.6 of the prongs extend inwardly of the socket afforded by the shell lfor several thirty-secondsof an inch. The prongs 21 and 22 are inherently resilient in nature,

and are oriented so that the corners 26 are in a leading position insofar ,as concerns thread movement :ofjthe lamp base during tightening of the latter in the shell.

Resultantly, the prongs'or resilient fingers .21 and 22' not only clasp the threaded'side wall of .the lamp base, but also the sharp corners 26 thereof take a bite on the side wall of the lamp base :at "spaced points thereon and" tendto prevent turningof-Ithe lamp inducedxbyvibration got the receptacle.

The prongs andfll he not provide :one hundred percentassuranceagainst backing o'tf of-ljthe 'lamp,*but ado afford appreciable resistance to this r'novemenhand in :the last or final fraction 0f an inch 10f possible extent .of

whack iofi" movement the prongs afford .a: slight :c'lasp on the lamp base tending to grip the same against dropping. The lamp receptacle at what constitutes the bottom thereof is formed with a, mounting'boss 30 presenting a recess 31 in which is mounted a coil spring 33. The coil spring 33 bears against the underside of the center contact 35 of the lamp receptacle, and imparts a spring biasthereto, urging the contact into positive engagement with the time before the resilient prongs on the receptacle shell lose their grip, so to speak.

Other and further objects of the present invention will be apparent from the following description and claimsandare illustrated in the accompanying drawings which,

byiway of illustration, show a preferred embodiment of the present invention 'and thefprinciplesthereof and what is now-con'sidered to be 'the bes't. mode contemplated forapplying these principles; iQther embodirnents the peripheral portion of thedisc ziftli that surrounds fthe center contact 2t of the lamp. The center contact 35, FIG. 3, includes an attaching flange 36 having an aperture 36A therein adapted to receive an attaching screw 37, FIGS. land 4, threadedly retained in the usual way within the receptacle base. I

The contact 35 includes an upwardly directed offset 40 ,whichterminates in a disc shaped portion 41'which is directly engageable with the center contactof the lamp base. The disc-portion "41' of the receptacle center contact includes an annular rim 4?; surrounding a depressed or concave portion 44. Thus, the-centerl contact of the receptacle includes a concavityand a rim thereabout respec tively complementalto the protruding le'ad bead 20B and lead bead as part of the center contact of the lamp.

Under and in accordance with the present invention the center contact of the receptacle includes a plurality of toothed extensions or sharp edge protuberances formed in the concavity 44 and in the rim 43. Thus, an extension 46 of rectangular form, FIG. 1, is struck upwardly from the concave portion 44 of the receptacle center contact as an integral part thereof, and a pair of extensions 47 of rectangular form are struck upward from the rim 43 as an integral part thereof, each such extension presenting sharp edges 49, FIG. 3, of which the sharp edge on the extension 46 will definitely bite into the soft lead bead B. Depending on the area extent of the bead 20B, one or both of the edges 49 presented by the prongs 47 will bite into peripheral portions of the bead 208 when the lamp is tightened in the socket presented by the shell '14. As a consequence, the prongs 46 and 47 assist the prongs 21 and 22 in resisting turning of the lamp in a loosening or backoif direction.

What is more, the extensions 46 and 47 in effect are extensions of the center contact of the receptacle, and hence one or more of these extensions will continue to bear against the lead bead 20B beyond that position of the lamp, undergoing loosening movement, which would ordinarily characterize a break between the contacts 20 and 35. Thus, a lamp associated with a lamp receptacle constructed under and in accordance with the present invention will not extinguish until after partaking of an appreciable extent of back-01f movement, due to vibration of the receptacle, and hence when this condition prevails, it is then known by the maintenance crew that the lamp has loosened and should therefore be tightened lest it drop from an overhead fixture.

While the present invention has been described from v the standpoint of the receptacle having a center contact with a separate spring bias, it will be appreciated that this aspect of the present invention is subject to considerable variation so far as concern a resiliently biased center contact and by the same token the receptacle can vary from the standpoint of the type of lamp retained therein. In any event, the sharp edge protuberances formed in the center contact of the receptacle are so located as to gouge or bite into the soft metal conductor bead as 20B included as a part of the center contact of the lamp, and because this head is readily deformable there will be a considerable amount of surface area in frictional contact, and actual impalement of the lead bead, supplementing the action of the prongs 21 and 22 beyond a mere multiplication of these parts. This is especially so in view of the fact that the extensions 46 and 47 are rectangular in nature, whereby each presents at least two sharp-edged right-angled corners and a connecting edge to the lamp contact. Additionally, the center contact extensions as 46 and 47 will maintain electrical contact with the base of the lamp throughout an appreciable portion of its back-off movement, and when contact is lost with the last of the extensions, the lamp will be extinguished thereby signalling an immediate need for retightening.

Hence, while I have illustrated and described a preferred embodiment of the present invention, it is to be understood that this is capable of variation and modification, and I therefore do not wish to be limited to the precise details set forth, but desire to avail myself of such changes and alterations as fall Within the purview of the following claim.

I claim:

In a lamp receptacle, a thin-walled retaining shell presenting a threaded socket member for retaining a lamp having a base with a complementally threaded side wall, and a circular center contact at the bottom of the base presenting at the medial part thereof a bead of soft conductor metal, a circular center contact at the bottom of the receptacle having a rim surface adapted to be engaged by the base of the lamp and said center contact of the receptacle also including a concave contact surface engageable with said bead associated with the center contact of the lamp, spaced prong elements struck inward from the receptacle shell and presenting sharp corners engageable with the side wall of the lamp base for resisting the tendency for the lamp to loosen in a back-off direction due to vibration of the lamp base receptacle, spaced sharp edge projections of rectangular form stnlck upwardly in cantilever fashion from portions of the rim each presenting a pair of sharp corners for engagement and electrical contact with the circular center contact at the base of the lamp as said lamp is threaded in said socket member, and a sharp edge extension of rectangular form struck upwardly in cantilever fashion from said concave contact surface and presenting a pair of sharp corners each adapted to gouge into and maintain electrical contact of thelamp whereby said projections and extension assist said spaced prong elements in resisting the tendency of the lamp to loosen in a back-off direction due to vibration of the lamp receptacle, and whereby the last of said projections and said extension of the receptacle to lose electrical contact with the base of the lamp, in the event of back-off vibration of the lamp, results in extinguishment of the lamp thereby giving an indication of the extent of back-01f vibration.

References Cited in the file of this patent UNITED STATES PATENTS 425,741 Bradley Apr. 15, 1890 803,246 Parnell Oct. 31, 1905 962,055 Rush June 21, 1910 2,146,011 Dame Feb. 7, 1939 2,326,370 Landmeier Aug. 10, 1943 2,379,063 Brown et al June 26, 1945 2,618,678 Gast Nov. 18, 1952 

